In the settings mentioned in earlier answers you can only change the main background and foreground colors, but if you want to for instance change the prompt, you have to set the PS1 env variable.

There are many examples that can be found with some googling, I use this (username in blue, path in green) for my black background:

PS1="\[\e[36;1m\]\u:\[\e[32;1m\]\w$ \[\e[0m\]"

Add that piece of code to a file called .bash_profile in your home directory (it's hidden, or most likely don't exist if you haven't used it for anything yet). You may also just enter the code in the terminal once to preview it.

Edit: More info here, Works in OS X even though they write about Linux.